This one is for Hib, others welcome to

[WhalePirot]

I have never seen higher oil pressure with a synthetic. Mobil's original brochure about Mobil One warned of lower, perhaps alarming oil pressure as the product if thinner. After putting it in my lil ole Pontiac, the pressure dropped waaay low, at idle.

I believe that the synthetics have superior high temperature protection.

I choose 'normal' Valvoline over the synthetics I have used in the past (both Mobil and Syntec). While I prefer a single grade oil, my choice of viscosity is 20W50, as it is never too cold here, and the single grades are either scarce or not sold.

Either choice will be just fine, as long as you change/check it regularly.

 

[Achilles]

I have never seen higher oil pressure with a synthetic. Mobil's original brochure about Mobil One warned of lower, perhaps alarming oil pressure as the product if thinner. After putting it in my lil ole Pontiac, the pressure dropped waaay low, at idle.

Thanks WhalePirot for your .02. I always thought that thicker oil would increase oil pressure. Reason being: cold oil- (thicker), high oil pressure. Hot oil-(thinner), low oil pressure.

Part of the other problem is that my TB is #%*! up and sucking air. As a result, I have an erratic idle that drops as low as 600 rpm. It's at this rpm level that oil psi drops to 17-19 psi. At 800 rpm, oil pressure is about 23 psi, which seems alot better. Hopefully when I get the TB replaced that will help somewhat. But again, this all happens when oil temp is about 185 -195. Under driving conditions (accelerating, cruising, etc.) oil pressure is good at mid to high 40's. And when the oil is cold, oil psi is much higher in the normal range of 45-52 psi.

So I'm leaning toward changing the oil to a higher viscosity. What do you think?

 

[WhalePirot]

I'm leaning toward changing the oil to a higher viscosity. What do you think?

Aside from the above, I'd surely find the air leak and solve it. You can spray WD-40 at suspect leaks, while the engine idles, and check for RPM changes.

I'd be concerned that at those low pressures, the top side parts are not getting a lot of oil. You could pull the oil filler cap and peek, or pull a valve cover and look.

In warmer climes, the owner's manual recommends higher viscosity oil. The thinner oils flow beter at very low temperatures and allow less resistance to moving parts; hence, somewhat improved fuel economy.

 

[Bill75]

Without intending to hijack the thread... maybe Paul (c4c5specialist) can answer whether this old shade-tree mechanic's trick really works...

If you've bought an older car and the oil looks pretty cruddy, pour a quart of automatic tranny fluid in a few days before you change the oil OR change the oil with some Kmart Blue-Light Special, a quart of ATF and a new filter, then run it for 1000 miles or so. Then upgrade to good quality oil & filter.

I've heard both of these recommendations in the past. Supposedly, this ATF is higher detergent and will clean up things, even helps unstick valve lifters, etc.

-Mac

Mac,

Years ago when detergent oils were first coming out we were cautious about using them in engines that were older and had always used non detergent oils; the fear was that the action of the detergent oil would break up sludge and circulate it thru the engine. This might be a real concern with an engine that has hydraulic lifters where the particles could clog them. So I'd be real concerned about putting something in an engine that wants to break up all the sludge and circulate it around. Just my opinion.

Bill

 

[Achilles]

Aside from the above, I'd surely find the air leak and solve it. You can spray WD-40 at suspect leaks, while the engine idles, and check for RPM changes.

I believe I know where the air leak is. The throttle linkage is wiggling (a lot) at the throttle butterfly shaft. So I am assuming it to be sucking air through the gap. The car runs fine after idle. I haven't checked to see if there is a TB rebuilt kit that may have a bushing replacement, if there is in fact a bushing in the body itself. That is for another thread in itself.

As far as the top end, I am very concerned about it getting enough oil. I'll take your advice and check it out. I know the temps (ambient) here haven't even begun to rise. We have 100 deg. plus summer ahead.

Thanks

 

[Achilles]

Well, I switched out the synthetic blend oil with conventional 10w-40 yesterday. Hoping that a higher grade of oil would improve oil pressure. The improvement was minimal, about 2 psi. Until I can get my idle situation taken care of, I'm going to have to keep a close watch on it. I may have to break down and replace the oil pump.

 

[Hib Halverson]

No, Hib I was running castrol GTX and felt that protection was very good. That is the reason I decided to switch to castrol syntec. However according to my brother Mobil 1 is superior to any motor oil convential or synthetic. So this is why I wanted to know if I could switch brands of synthetic oils.

Sorry for the confusion

Craig

Your brother is correct.

Castrol Syntec is a highly-refined, petroleum-based oil and not a true synthetic oil in the way petrochemical engineers look at engine oil base stocks. Castrol USA gets away with calling it a synthetic because of an arbritration it won against Mobil Oil Corporation over the issue and that consumers and the FTC are not demanding enough. Don't get me wrong. This doesn't mean that Castrol Syntec is unacceptable for use in lubricating an engine, it just means that when stacked up against Mobil 1 or Red Line, it's decidely a third choice when performance and protection are key factors in a purchase decisiton and only becomes a first choice when price is the prime factor in a purchase decision.

Mobil 1 is a synthesized hydrocarbon-based product which has somewhat better protection available to an engine when the oil is subjected to high-temperature, high-shear conditions. The best Mobil 1 to use is the 10W30. What's sad is the M1 used to have an even better formula but Mobil Oil Corp.s loss to Castrol in that arbritration forced it to slightly degrade the M1 formula to keep it price-competitive in the market place. M1 still remains a better choice for engine oil than Syntec but it's not quite as better as it was at one time.

The comment was made elsewhere in the thread that Red Line is the best of them all. That is true. Red Line engine oils use an ester-base stock which makes them even better than Mobil 1 for protection of engines subject to extreme duty.

In my own vehicles, I use Red Line---10W30 for any engine with cats and SAE30 Race Oil in any engine without cats.

 

[vetteboy86]

So because the castrol isn't a true synthetic, will I have a problem switching to it? I have heard that the synthetics have detergents that break up engine sludge. When I first switched to castrol, I ran the motor 500 miles then changed the oil, and have been running the oil around 3500 miles. Thanks for the info.

Craig

 

[Hib Halverson]

So because the castrol isn't a true synthetic, will I have a problem switching to it? I have heard that the synthetics have detergents that break up engine sludge. When I first switched to castrol, I ran the motor 500 miles then changed the oil, and have been running the oil around 3500 miles. Thanks for the info.

Craig

Urban legend.
Switch and enjoy.

 

[vetteboy86]

Thanks Hib, any special blend that you would recommend. I see the commercial where they have the three different mile interval oils.

 

[G Winter]

the mobil 3000 mile oil is not synthetic. the other two are. seems they upgraded thier synthetic oil and now have two grades. next time around I may go to the top of the line .

 

[milehigreg]

Just thought I would run this up the flag pole. I believe that the oil pump on engines is a positive displacement pump. This means that as long as there is fluid avaialble at the intake, that fluid will be moved through the pump and into the system. It follows then that with a thicker fluid ( higher visciosity ) the system oil pressure would be higher and vice versa with lower viscosity since the same flow through the system occurs from the pump with either. Therefore, low oil pressure with a thinner oil is to be expected and does not mean there is less oil flow through the system. Further, it seems to me that thinner oil which induces less pressure drop though the system and therefore less pressure would flow more easily to all parts of the system. I'll let someone else discuss how the oil actually behaves on the bearing surfaces thick vs thin, bearings vs rings, rings vs valve train.

 

[Hib Halverson]

Thanks Hib, any special blend that you would recommend. I see the commercial where they have the three different mile interval oils.

To me a "blend" means one of those semi-synthetic blends, which I wouldn't use.

Put full/true/all synthetic Mobil 1 10W30 in your engine.

 

[Evolution1980]

To me a "blend" means one of those semi-synthetic blends, which I wouldn't use.

Put full/true/all synthetic Mobil 1 10W30 in your engine.

Hib, since you appear "online" right now and you have given a definitive answer to the original question asked, let me throw in my questions here.

I have the ZZ4 engine ("no cats", since you mentioned that spec above)
I've always used M1 Full Synth 10W30 since I had the engine (except for the 500 mile break in when I used the dinosaur bones).

My car only runs in the summer. Air temps get anywhere between 65° and 90°. Sometimes I run the car like I'm trying to break the sound barrier, other times I just cruise above an idle.

The Questions:
1) What happens, or is there a problem, in using a 50/50 mix of 2.5qts 5W30 and 2.5qts 10W30? (I'm thinking that I could gleen a little bit of the good features from each...)

2) What is the approximate cost difference in RedLine -vs- M1? If I was to switch to RedLine, which one would you suggest and do you have a preferred vendor? (I haven't seen it in any of the shops in NE Ohio).

 

[LT4man]

Check out the oil tests that Amsoil has run. Some amazing and unusual results.

http://www.amsoil.com

"Comparing Amsoil to the Competition"

Save The Wave!